Plastic surfacing material and the process of producing same.



- Same,

'to be a full, clear,

' become very brittle,

' of Illinois,

JOHN C. MER'IENS, OF CHICAGO, ILLINOIS.

No Drawing.

- I To all whom it may concern:

Be it known that I, JOHN (1. Manama, a citizen of the United States,.and a resident of Chicago, county of Cook, and State have invented certain new and useful Improvements in Plastic Surfacing Material and the Process of Producmg the of which the following is declared and exact descriptiom My invention relates to plastic surfacing material and to the process of producing the same, and its primary object s to produce a surfacing material, such asls suitable for use in paving roadways and the like, which shall be waterproof, tough, tenacious and dense, and yet malleable. Heretofore aving materials of this general class have een formed of a filler comprising rock, crushed stone, sand or gravel, or combmations of those substances mixed with a binder such as asphaltor other bituminous substances. In those paving materials the asphalt or bituminous substance acts merely as a binder between the surfaces of the rock, crushed stone, sand or gravel and cements them together as it were. It has also been proposed to use soil, clay or loam as a filler. ihe principal objection to pavements commonly in use, which employ a bltumlnous binder, is that when subjected to the rays of the summers sun they become soft and plastic, and when subjected to cold weather, they and the surface breaks readily when subjected to traflic. It is the aim of the present invention to eliminate these objectionable features by fproviding a waterproof pavement capable 0 ing wide ranges of temperature, whereby the surface may remain even, smooth. and unbroken, subject only to the wear occasioned by the traflic.

The invention consists therefore m a new and improved process of producing surfac- -material, suitable for paving roadways and the like, which consists in combining pulverized or finely divided limestone (to which may be added a portion of finely pulverized shale) with a hot 1i uefied b1tumi nous binder, and in the resu ting material which is homogeneous, yet malleable, waterproof, tough, tenacious and dense, and consequently forms an ideal surfacing material for the purpose of paving roadways and the like.

Specification of Letters Patent.

withstand- Patented Aug. '7, 191?.

Application filed May 8, 1916. Serial No. 96,063.

I take finely pulverized limestone, substantially free from sand, gravel clay or soil, (to whlch' may be added, if esired, a port1on of finely pulverized shale), heat the same, and when hot impregnate the same with a hot liquefied bituminous binder, such asasphalt, by thoroughly mixing the ingred ients. While the exact proportions of the lngredients employed are not essential to this invention, broadlyconsidered, yet I have found that by using approximately it} per cent. bitumen to 84 per cent. of finely divided limestone, most excellent results are obtamed. After the composition has been thoroughly mixed, it may be compacted by pressure as for instance by rolling it to form a pavement, which is wate roof, homo geneous, tough and tenacious, gense yet malleable, absolutely dustless under friction and practically indestructible. I have found it desirable to use a high penetration asphalt, which is more readily absorbed by the filler and makes the resulting material malleable at all times and does not soften in summer, for .the reason that the bitumen is wholly perfectly absorbed by the filler.

In order to obtain a uniform and complete impregnation with the hot liquefied bituminous binder, I have discovered that the filler, that is to say, the finely dividedlimestone, must be thoroughly dry, and in addition, must be hot when the binder is introduced. This material cannot be pro erly impregnated with the hot liquefied bituminous binder unless it is very finely pulverized and unless in a substantially dry condition.

In contra-distinction to the fact above mentioned, namely, that heretofore a bituminous binder merely acts to coat the pieces of rock, crushed stone, sand or gravel, andis left in a free state, I have discovered that when a hot liquefiedbituminous binder is incorporated with a finely pulverized limestone, the resulting product becomes, when compacted, a waterproof, homogeneous, tough and tenacious substance, the binder being absorbed in the finely divided particles in such a way that it is not affected or caused to soften'under high temperatures such as the heat of the summers sun, nor is it aifected by water, and the consequence is that a surfacing material composed of the substances speclfied and combined as hereinbefore described is not only waterproof In carrying out the present invention I and dustless, presenting asmooth and dense 11o surface .at 'all temperatures, but positively retains the form given it when rolled or compacted into shape.

The process which I have described is independent of any particular machme or apparatus for carrying out the same, but the ingredients can be mlxed n the ordinary asphalt plant. For commercialpurposes, 1t is desirable to' use pulverized limestone and shale, such as is now being manufactured by numerous cement plants throughout the country, inasmuch as this material is obtamable at such cement plants and is very cheap because of its being a raw material and can be transported in open cars at a ow cost. The only reason for combining the shale with the limestone is that all cement plants,

in manufacturing raw material for cement,

mix about 14 per cent. shale with the limestone; this shale is not necessary in the making of my roadway surfacing materlal, 1nasmuch as it does not benefit or injure the products in any way; in other words it may be added to the pulverized limestone or left out as is found convenient or expedient.

To those familiar with the art to which this invention pertains, it will be readily apparent that paving material produced in accordance with the above specified fprocess and containing the materials speci ed, or their equivalents, more nearly approaches a state of perfection than any other'paving material known at the present time, for the reasons that my present paving material is waterproof, tough and tenacious, dense and malleable and absolutely uniform because the pulverized limestone, after being heated, readily absorbs the hot bitumen when mixed therewith. With the use of finely pulverized limestone the resulting material does not fracture under the impact or friction of trafiic, whereas in my experience I have found that the reason for other classes of bituminous pavements wearingv out, is that the mineral aggregate of which such roadway paving materials are composed, is a very hard, brittle substance such as rock, crushed stone, gravel or sand mixed with bitumen of apparently very low penetration, which becomes very hard and brittle under low temperatures, and the bitumen and mineral aggregates are fractured under the action of trallic, and are ground up into dust which is either blown or washed away. I am aware that it has been proposed to produce a surfacing material from soil, clay or loam mixed with asphalt, but the resulting material in my opinion, is not waterproof, since soil, clay and loam have a great affinity for water, and soon absorbs moisture and water, and the pavement becomes soft and plastic. I therefore disclaim the use of sand, gravel, rock, or crushed stone other than limestone or shale or soil as a base or filler for my surfacing material.

The process which has been particularly described admits of substitutions and variations of the ingredients and proportions, wherefore the right is reserved to all substitutes and ingredients and proportions as are equivalent to those which are mentioned in the appended claims.

I claim as new and desire to secure by Letters Patent 1. The process of producing surfacing material, sultable for paving roadways and the like, which consists in mixing together pre-heated, hot pulverized limestone and shale, substantially free from other rock, or crushed stone and sand, or soil, and hot liquefied bitumen in the proportion of 84 per cent. limestone and shale and 16 per cent. bitumen.

2. The herein described process of producing surfacing material, suitable for paving roadways and the like, which consists in mixing hot finely divided limestone and shale, substantially free from other rock or crushed stone and sand, gravel or soil, with pre-heated, hot liquefied bitumen, and thereby thoroughly impregnating the limestone and shale with the bitumen.

3. A new composition of matter, suitable for use in surfacing roadways and the like, comprising a filler composed exclusively of pulverized limestone and shale, and a binder of bitumen, all pre-heated and'mixed together while hot, and thereafter compacted.

JOHN C. MERTENS.- 

